Rotor for a cooling fan

ABSTRACT

A rotor for a cooling fan has a hollow hub having an open lower end. A permanent magnet is received in the hub. A rod is received in the hub and extends downwards. Multiple vanes are evenly formed around the periphery of the hollow hub and extend radially. Multiple notches are respectively defined at edges of the vanes and adjacent to the hollow hub. When the airflow is compressed by the rotation of the vanes, the airflow can be led to a desired direction via the notches. Whereby, the pressures between adjacent vanes are even thereby preventing the collision between the airflow and interior components of the cooling fan, so that the noise is avoided.

BACKGROUND OF THF INVENTION

1. Field of the Invention

The present invention relates to a rotor for a cooling fan, and more particularly to a rotor which can avoid noise when operating.

2. Description of Related Art

Generally, electrical units such as CPUs (Central Processing Unit) or power supplies in various electrical machines give rise to heat when operating. A working efficiency of the electrical units will decrease if the heat is not radiated. Hence, a cooling fan is provided on the electrical units to reduce the temperature. With a substantial steady air output which will not be affected by an external airflow around the fan, a lateral-blowing cooling fan has a good heat radiating effect and is widely used.

With reference to FIGS. 6-7, a conventional lateral-blowing cooling fan (30) comprises a hollow base (31), and a cap (32) defined with an air inlet (321). A chamber (33) is defined in an interior of the hollow base (31) and an air outlet (331) is defined in a side of the hollow base (31) and communicates to the chamber (33). A stator assembly (35), which is composed of yokes, coils, a circuit board, etc, is received into the chamber (33). A rotor (34) with multiple vanes (341) is rotatably mounted on the stator assembly (35) and a permanent magnet (not shown) is provided in the rotor (34). Hence, when the stator assembly (35) is powered on, the rotor (34) is driven to rotate about the stator assembly (35), so that airflow from outside can flow into the chamber (35) through the air inlet (321), and is compressed in the chamber (33) through the rotation of the vanes (341). Then, the airflow is laterally discharged from the air outlet (331) to provide a good radiating efficiency.

However, when the vanes (341) push the airflow, an airflow distribution between adjacent vanes (341) can not be absolutely even, so pressure differences may be formed between the vanes (341). Because there is no airflow guiding means provided in the conventional cooling fan, the airflow may collide with interior components of the cooling fan (30) thereby generating a noise during operation of the cooling fan (30).

Therefore, the invention provides a rotor for a cooling fan to mitigate or obviate the aforementioned problem.

SUMMARY OF THE INVENTION

The main objective of the present invention is to provide a rotor for a cooling fan which can avoid noise when the cooling fan is operating.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rotor for a cooling fan in accordance with the present invention;

FIG. 2 is a top view of the rotor for the cooling fan in accordance with the present invention;

FIG. 3 is a cross sectional view of a vane of the rotor for the cooling fan in accordance with the present invention;

FIG. 4 is an exploded perspective view of the cooling fan in accordance with present invention;

FIG. 5 is a cross sectional view of the cooling fan in accordance with the present invention;

FIG. 6 is an exploded perspective view of a conventional cooling fan; and

FIG. 7 is a top view of a rotor of the conventional cooling fan.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1-2, a rotor (10) for a cooling fan comprises a hollow hub (11), and multiple evenly-placed vanes (12) formed around a periphery of the hollow hub (11) and extending radially. Each of the vanes (12) has a notch (13) defined in an edge thereof and adjacent to an outer periphery of the hollow hub (11). The hollow hub (11) has an opening end defined at a lower end thereof, a permanent magnet received in an interior thereof, and a rod (111) axially provided in a center thereof and extending downwards.

With reference to FIG. 3, a bevel (131) is formed on a bottom of each notch (13). In this embodiment, the notch (13) is defined at a top edge of each vane (12). In another preferred embodiment of the present invention, the notches (13) can be defined in bottom edges of the respective vanes (12). Furthermore, the notches (13) are defined adjacent to the outer periphery of the hollow hub (11), so that an area of a middle portion and distal portion of each vane (12) contacting with airflow is not decreased. Therefore, the vanes (12) still can effectively push the airflow when the rotor (10) is rotated. Therefore, an effective function of enabling the airflow to go to a desired direction is not impaired when the rotor (10) for the cooling fan is operating.

With reference to FIGS. 4-5, the rotor (10) is provided in a base (20) of a cooling fan. The base (20) has a chamber (21) defined in an interior thereof, and an air outlet (211) defined in a side thereof and in communication with the chamber (21). A stator assembly (23) is received into the chamber (21) and the rod (111) is rotatably connected to the stator assembly (23). A cap (22), in which an air inlet (221) is defined, is detachably mounted over the chamber (21).

In operation, when the stator assembly (23) is powered on to excite the permanent magnet, the rotor for the cooling fan is driven to rotate in the chamber (21). Hence, the airflow can enter the air inlet (221) via the rotation of the vanes (12) and progress to the chamber (21). Furthermore, the airflow is compressed in the chamber (21) and is pushed out from the air outlet (211) to radiate heat of the base (20) acquired from a heat-generating component that the base (20) abuts.

Additionally, when the airflow is compressed by the rotation of the vanes (12), the airflow can be led to a desired direction via the notches (13) with respective bevels (131). Hence, the pressures between adjacent vanes (12) are even thereby preventing the collision between the airflow and interior components of the cooling fan, so that the noise can be avoided.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A rotor (10) for a cooling fan comprising: a hollow hub (11) having an open lower end, a permanent magnet received in the hub (11), and a rod (111) axially received in the hub (11) and extending downwards; multiple vanes (12) evenly formed around an outer periphery of the hollow hub (11) and extending radially; and multiple notches (13) respectively defined in the vanes (12) and adjacent to the outer periphery of the hollow hub (11).
 2. The rotor (10) for the cooling fan as claimed in claim 1, wherein the notches (13) are defined in a top edge of the respective vanes (12).
 3. The rotor (10) for the cooling fan as claimed in claim 2, wherein a bevel (131) is formed at a bottom of each notch (13).
 4. The rotor (10) for the cooling fan as claimed in claim 1, wherein a bevel (131) is formed at a bottom of each notch (13). 